Molecular sieves are a commercially important class of crystalline materials. They have distinct crystal structures with ordered pore structures which are demonstrated by distinct X-ray diffraction patterns. The crystal structure defines cavities and pores which are characteristic of the different species.
Molecular sieves are classified by the Structure Commission of the International Zeolite Association (IZA) according to the rules of the IUPAC Commission on Zeolite Nomenclature. According to this classification, framework type zeolites and other crystalline microporous molecular sieves, for which a structure has been established, are assigned a three letter code and are described in the “Atlas of Zeolite Framework Types,” Sixth Revised Edition, Elsevier (2007).
ERI framework type materials are characterized by three-dimensional 8-membered-ring pore/channel systems containing double-six-rings (d6r) and cages. Small pore zeolites containing d6r building units and cages have shown utility in methanol-to-olefins catalysis and in the selective catalytic reduction of nitrogen oxides (NOx)to name some of the more important commercial applications.
U.S. Pat. Nos. 9,409,786 and 9,416,017 disclose an ERI framework type molecular sieve designated SSZ-98 and its synthesis using N,N′-dimethyl-1,4-diazabicyclo[2.2.2]octane dications as a structure directing agent.
It has now been found that 1,3-dicyclohexylimidazolium cations are effective as a structure directing agent in the synthesis of SSZ-98.